| 摘要 |
PROBLEM TO BE SOLVED: To enable a precise rotating precision measurement by removing the influence on measurement by rotation unevenness, use of a window function, or the like. SOLUTION: A detection signal Sd showing the displacement of a rotator is inputted to a DC cut part 111 as digital data, and the DC cut part 11 removes DC components from the digital data and outputs the result as collection data Da. A periodic separation part 112 obtains block data Db by separating the collection data Da into blocks every rotating period. A rate conversion part 113 uniforms the data number (sampling number per rotating period) of each data block constituting the block data Db by rate conversion. A signal processing part 114 calculates spectrum data by subjecting the rate-converted block data Dc to FFT without using the window function, and determines an index showing the rotating precision such as NRRO value on the basis of the spectrum data. COPYRIGHT: (C)2003,JPO
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